1. Field of the Invention
The invention relates to an overhead barrier warning system. More particularly, the invention relates to a visual and audible vehicular overhead clearance warning system to warn and deter tall vehicle operators not to enter or travel on restricted roadways that have low overhead clearance bridges.
2. Prior Art
Insufficient overhead clearance for tall vehicles is a well known traffic control problem. Every year, many lives are lost in accidents caused by tall trucks and buses attempting to pass under a low bridge or overpass. Even in cases where the accidents do not result in personal injuries, they always result in large traffic delays. These delays increase fuel consumption and air pollution and waste many hours for commuters. Substantial governmental resources are expended in removing tall vehicles which are stuck under a low bridge or overpass. The bridge or overpass is often damaged and requires repair. In any event it must be inspected for safety. The tall vehicle is always severely damaged, sometimes irreparably and it is thus taken out of service resulting in economic loss to many parties. Delivery of cargo carried by the tall vehicle is delayed and sometimes the cargo is damaged or destroyed.
It is common practice today to place highway overhead clearance signs on vertical posts imbedded in the ground on the shoulders of roadways before low bridges or at intersections where roadways lead to low clearance bridges. In rare instances overhead clearance signs are displayed over the roadway but they are the exception.
Signs that are posted to warn tall vehicles of the height clearance of a bridge ahead, can, at certain times, be difficult to see and/or interpret. Overhead clearance signs on vertical posts for eye level viewing suffer from a number of disadvantages. In northern climates ice, snow, rain, and fog often reduce a driver's visibility and consequently informational signs on vertical posts at eye level often times lose their effectiveness. Poor and infrequent maintenance of highway informational overhead clearance signs on vertical posts allows the words and numbers to weather and as a result the message displayed can become difficult to read or interpret. The overgrowth of vegetation near highway clearance signs mounted on vertical posts often covers or obscures the warning message displayed. At times these important overhead clearance warning signs that are mounted on vertical posts get knocked down and immediate replacement is not always accomplished. A common form of mischief that takes place today is the rampant and uncontrolled graffiti writing that is applied to highway informational signs used to warn motorists of highway hazards such as low bridges or to warn commercial traffic to stay off certain roadways or parkways with extremely low bridges. Informational signs damaged by graffiti are difficult or impossible to read.
Traffic informational clearance signs mounted on posts are usually placed before or at an intersection to alert truck or bus drivers of the maximum overhead clearance on the roadway ahead. In heavy traffic conditions a driver's view of an eye level warning clearance sign can easily be obstructed by other vehicles and therefore a tall vehicle can inadvertently enter a restricted roadway meant only for passenger cars. Operators of tall motor vehicles on a roadway without adequate overhead clearance warning signs are vulnerable and might impact a low bridge ahead.
The use of overhead chains suspended from a horizontal member mounted on a vertical pole above a roadway without accompanying informational signs does not adequately deal with the prevention or deterrence of tall motor vehicles from entering restricted roadways. These chains do not present a highly visible warning to the operators of tall vehicles. A vehicle which impacts a suspended chain will not necessarily make enough noise to alert the driver to the dangerous condition of a low bridge ahead.
U.S. Pat. No. 4,346,666 to Iso discloses a console traffic direction post which includes a horizontal arm carrier on a vertical support member and a reflector suspended from the horizontal arm carrier. The direction post is less subject to occlusion by snow in the winter, is less likely to be damaged, and is inexpensive to maintain. It does not, however, address the particular problems associated with overhead clearance warnings.
U.S. Pat. No. 3,631,619 to Campbell discloses an overhead traffic informational or directional sign which is suspended from the roof of a tunnel and is elongated in the direction of the movement of the traffic resulting in a condition called anamorphosis. This results in a sign which is less likely to be obscured by other vehicles. It is inapplicable as an overhead clearance warning, however.